/* Create /proc/self/fd-related names for subfiles of open directories.
Copyright (C) 2006 Free Software Foundation, Inc.
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2, or (at your option)
any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software Foundation,
Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA. *//* Written by Paul Eggert. */
#include<config.h>
#include"openat-priv.h"
#include<sys/types.h>
#include<sys/stat.h>
#include<fcntl.h>
#include<stdio.h>
#include<string.h>
#include"dirname.h"
#include"intprops.h"
#include"same-inode.h"
#include"xalloc.h"/* The results of open() in this file are not used with fchdir,
therefore save some unnecessary work in fchdir.c. */
#undefopen
#undefclose
#definePROC_SELF_FD_FORMAT"/proc/self/fd/%d/%s"
#definePROC_SELF_FD_NAME_SIZE_BOUND(len) \
(sizeof PROC_SELF_FD_FORMAT - sizeof"%d%s" \
+ INT_STRLEN_BOUND (int) + (len) + 1)
/* Set BUF to the expansion of PROC_SELF_FD_FORMAT, using FD and FILE
respectively for %d and %s. If successful, return BUF if the
result fits in BUF, dynamically allocated memory otherwise. But
return NULL if /proc is not reliable. */char *
openat_proc_name (char buf[OPENAT_BUFFER_SIZE], int fd, charconst *file)
{
staticint proc_status = 0;
if (! proc_status)
{
/* Set PROC_STATUS to a positive value if /proc/self/fd is
reliable, and a negative value otherwise. Solaris 10
/proc/self/fd mishandles "..", and any file name might expand
to ".." after symbolic link expansion, so avoid /proc/self/fd
if it mishandles "..". Solaris 10 has openat, but this
problem is exhibited on code that built on Solaris 8 and
running on Solaris 10. */int proc_self_fd = open ("/proc/self/fd", O_RDONLY);
if (proc_self_fd < 0)
proc_status = -1;
else
{
struct stat proc_self_fd_dotdot_st;
struct stat proc_self_st;
char dotdot_buf[PROC_SELF_FD_NAME_SIZE_BOUND (sizeof".." - 1)];
sprintf (dotdot_buf, PROC_SELF_FD_FORMAT, proc_self_fd, "..");
proc_status =
((stat (dotdot_buf, &proc_self_fd_dotdot_st) == 0
&& stat ("/proc/self", &proc_self_st) == 0
&& SAME_INODE (proc_self_fd_dotdot_st, proc_self_st))
? 1 : -1);
close (proc_self_fd);
}
}
if (proc_status < 0)
return NULL;
else
{
size_t bufsize = PROC_SELF_FD_NAME_SIZE_BOUND (strlen (file));
char *result = (bufsize < OPENAT_BUFFER_SIZE ? buf : xmalloc (bufsize));
sprintf (result, PROC_SELF_FD_FORMAT, fd, file);
return result;
}
}